299.
THE PLASMA LEVELS OF GMP-140 ET-1 AND NPY IN NEW COMERS AT ALTITUDE
OF 3702. M. Li Zhan-Quan
1
, Wang Hong-Xin
1
, Jia Nai-Yong
1
, Li Yu-Li
1
, Li Xue-Mei
1
. Dept. of
Hematology, Qinghai Medical College Hospital, Xining, Qinghai, P.R. China.
1
.
The platelet granule membrane protein (GMP-140) is a more specific and direct marker than
others for estimating of platelet activation. The endothelin-1 (ET-1) can affect platelet function,
and neuropeptide Y (NPY) is released from the aggregate platelets. Some studies have confirmed
that there is elevated degree of platelet activation in immigrants at high altitude and plasma levels
of ET-1 and NPY were also increased when the subjects rapidly ascended to high altitude. In
present study we investigated the interrelationship between the plasma GMP-140, ET-1 and NPY
levels and hypoxic exposure. METHODS: The venous plasma GMP-140, ET-1 and NPY
concentrations were investigated by competitive radioimmunoassay in 42 immigrants (all male,
17-24 years old) originally from Xining (2261 m) and living at Jiegu ( 3702m) for from 3 months
to 3 years. These plasma concentrations were compared with those in 36 residents (all male, 20-
24 years old) in Xining. Platelet count of peripheral blood was performed in all subjects.
RESULTS: Compared with the Xining residents with GMP-140 level of 24.0±7.0ug/L and NPY
level of 99.9±34.5ng/L, the level of GMP-140 (30.5±10.0ug/L) was increased and the NPY level
(79.8±25.0ng/L) was decreased in the immigrants (p_0.01). No significant difference of ET-1
level was found between two groups. There were not any correlations among data.
CONCLUSIONS: These results suggest that the higher degree of platelet activation is further
confirmed in the Jiegu immigrants, and the elevated platelet activation is not caused by
circulating ET-1 and does not increase the plasma level of NPY.
300.
EFFECT OF HYPOXIA ON THE PROLIFERATION OF EMBRYONIC STEM CELLS.
Huiqing Zhao
1
, Lingling Zhu
1
, Tong Zhao
1
, Haisheng Li
1
, Liying Wu
1
, Aishi Ding
1
, Ming Fan
1
.
Institute of Basic Medical Sciences
1
.
Objective: To investigate the effects of intermittent and persistent hypoxia on the
proliferation of mouse embryonic stem cells (ES cells) in vitro. The topic comes from the fact
that early embryonic development is in the hypoxic environment (3%) and previous study shows
that hypoxia promote the proliferation of the placental trophoblast cells and CNS precursors.
Methods: 1) The cells were treated with gases (containing 3% or 10% oxygen) in a sealed
chamber. 2) The proliferation of ES cells was measured by BrdU-labeled flow cytometer (FCM).
3) The expression of hypoxia inducible factor-1a (HIF-1a) was detected by RT-PCR. Results: 1.
The number of BrdU-labeled ES cells cultured in hypoxia (3% and 10% O2) could not change
compared with the control (20% O2) after 24 hours cultivation. 2.When ES cells were
respectively stimulated by intermittent hypoxia (O2 concentration: 3% and 10%) for 10 minutes
per day for 4 days, the proliferation of ES cells in the 3% O2 group was promoted significantly,
whereas, the proliferation of ES cells in the 10% O2 group inhibited compared with that in
control. 3. The expression of HIF-1a ES cells cultured in either normoxia or hypoxia (3% and
10% O2) has no significant change. Conclusions: Intermittent hypoxia (3%) can significantly
promote the proliferation of ES cells in vitro, while persistent hypoxia could not. This response
may be not involved in the expression of HIF-1. The mechanism of proliferation of ES cells
stimulated by intermittent hypoxia should be studied in the future. The work was supported by
key grant of Natural Sciences Foundation of China (30393130)
301.
REGULATION OF LONG TERM HYPOXIA (LTH)-INDUCED CHANGES IN
NOREPINEPHRINE (NE)-INDUCED CONTRACTION AND CA2+ SENSITIVITY IN OVINE
CEREBRAL ARTERIES. Yu (Joy) Zhao
1
. Loma Linda University
1
.
We have reported that LTH decreases NE-induced cerebral artery contractions, with
increased Ca2+ sensitivity. We tested the hypothesis that LTH-induced changes in vessel
contractility and Ca2+ sensitivity are regulated by the phosphorylation of myosin light chain20
(MLC20) via the RhoA and CPI-17 pathway. In both normoxic and hypoxic ovine cerebral
